The enamel layer of the tooth is naturally an opaque white or slightly off-white colour. However, this enamel layer can become stained or discoloured. The enamel layer of the tooth is composed of hydroxyapatite mineral crystals that create a somewhat porous surface. It is believed that this porous nature of the enamel layer allows staining agents and discolouring substances to permeate the enamel and discolour the tooth.
Many products we consume have a negative impact on our teeth and mouth. Many substances can stain or reduce the whiteness of one's teeth, in particular, certain foods, tobacco products, and fluids such as tea and coffee. These staining and discolouring substances are often able to permeate the enamel layer. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one's teeth.
Consumers have always had a strong desire for white teeth and many individuals are dissatisfied with their current teeth colour. This desire for whiter teeth has given rise to a growing trend in the increased use of tooth whitening products.
A variety of products are currently used for teeth whitening. Such products often comprise peroxides, abrasives or both in order to clean and whiten teeth. These types of products are often not desired since they do not contribute to the remineralization of teeth and can cause damage to teeth and gums if overused. Products comprising calcium source have been developed in an attempt to enhance the characteristics of teeth. Such products, however, do not positively adhere to teeth and thereby may only contact teeth for a brief period of time prior to being rinsed out of the mouth in wash water.
The inventors have now recognized a need to develop an oral care product which is suitable to whiten teeth and also gentle for use. It has been found that calcium silicate, especially calcium silicate in the form of a hydrate can behave as a deposition aid and unexpectedly enhances the deposition of particulate tooth whitening agent on tooth surfaces to provide instant tooth whitening benefit. Particularly, the presence of calcium silicate hydrate as a deposition aid in an oral care composition can greatly improve the adherence of particulate tooth whitening agents to the surface of the teeth for a long enough period of time to provide not only instant but also excellent long-lasting tooth whitening benefits.